As the UK braces for extreme heat with temperatures forecast to reach 37C in London on Wednesday under a Met Office red warning, health experts are urging the public not to use electric fans. Official government guidance states that fans become ineffective above 35C and may actually exacerbate dehydration.
Met Office Red Warning and Temperature Forecast
The Met Office has issued a red warning for extreme heat, effective from midnight on Wednesday until 9pm on Thursday. London is expected to hit at least 37C on Wednesday, while most of the 148 UK areas under weather warnings will see temperatures of 35C or above on Wednesday or Thursday. Friday's temperatures in London are still predicted to reach 36C.
Why Fans Are Not Recommended
According to the UK Health Security Agency (UKHSA) heatwave guidance, electric fans are only effective when the air temperature is below 35C. The guidance states: "Homes can overheat and become uncomfortable during warmer weather, particularly when you are trying to sleep. Use electric fans if the air temperature is below 35C, but do not aim the fan directly at your body as this can lead to dehydration."
Fans circulate air but do not cool the room. Relying on them can give a false sense of security, leading to neglect of proper hydration or room cooling. In temperatures above 35C, fans may actually increase the room temperature by moving hot air around.
Alternative Cooling Advice
The government recommends shading windows, increasing airflow, closing curtains, staying hydrated with regular water intake, taking cold showers, and avoiding direct sunlight. These measures are crucial as climate change drives higher temperatures. The UKHSA notes that all the warmest years on record in the UK have occurred since 2002, and in July 2022 temperatures exceeded 40C for the first time. An estimated 2,803 people aged 65 and over died due to heat in England in 2022, and heat-related deaths may triple by 2050.
Health Risks and Vulnerable Groups
Hot weather increases the risk of heart attack, stroke, lung problems, and other diseases. Older people, babies, young children, and those with underlying medical conditions are more vulnerable. The UKHSA works with the Met Office to issue health alerts during hot weather to help protect the public.
